1. Field of the Invention
This invention relates broadly to an electrical apparatus. More particularly, this invention relates to an electrical apparatus for use with appliances having inductive loads which corrects the power factor of the appliance circuit.
2. State of the Art
In a typical AC electric circuit, there is a time delay between when the voltage pushes an electrical current, and when that electrical current actually begins to flow. The duration of this time delay is one measure of the “Power Factor”.
Currently, industrial countries generate most of their electricity in large centralized facilities, such as coal, nuclear, hydropower or gas powered plants. These plants have excellent economies of scale, but usually transmit electricity long distances. Most plants are built this way due to a number of economic, health & safety, logistical, environmental, geographical and geological factors. For example, coal power plants are built away from cities to prevent their heavy air pollution from affecting the populace, in addition such plants are often built near collieries to minimize the cost of transporting coal. Hydroelectric plants are by their nature limited to operating at sites with sufficient water flow.
Distributed generation is another approach. It reduces the amount of energy lost in transmitting electricity because the electricity is generated very near where it is used, perhaps even in the same building. This also reduces the size and number of power lines that must be constructed. Typically, distributed generation does not replace the utility network but rather supplements it. Excess energy produced by distributed generators is fed back into the network and the utility company purchases it from the customer who generated it. Unfortunately, high power factor distributed generation typical in modern “green” generating technologies, within customer premises reduces the power factor at the utility service entrance.
Power factor can also be expressed as the ratio of real power on the network to apparent power. The theoretical ideal power factor ratio is one. The two components of apparent power are real power and reactive power. Real power is the component for which the utility company bills its customers. Reactive power is an undesirable byproduct of having inductive loads (e.g. motors and transformers) connected by customers to an AC distribution system. Its characteristic is that the current waveform lags behind the voltage waveform. This results in higher operating currents and higher related thermal losses occurring throughout the system. Small appliances with motors, particularly air conditioners, generally have the worst power factor with respect to the size of the load they represent. In addition, air conditioners draw their power when the utility network is most heavily loaded. Also, as distributed generation proliferates, with less real power being delivered by the utility and reactive power remaining constant, the power factor of the utility network will decrease and the network may become unstable.